Powered nail drivers utilizing nail feed clips and pneumatic feed tubes are old in the art for feeding a high volume of nails classified as common nails, as where the diameter of circular flat heads are generally more than twice the diameter of the shanks. In feeding such conventional nails progressively to a powered driver, the heads of the nails either are coplanar and spaced, or are disposed edge-to-edge in a transport train, or are axially offset enough to overlap vertically with the head of the lead nail contacting the adjacent shank on the next nail head above it. In most cases, however, unless supported in an inclined clip member the nails are carried on a feed tape means or a frangible adhesive that supports the nails as a stick unit.
In feeding a train of nail heads in edge-to-edge contact by a resilient force under working conditions, the contacting edges of the heads can become overlapped and cause malfunctions because there is only a critical single point of contact between adjacent nails whose nail head edges are rounded in two directions. In feeding overlapping heads there are theoretically two contact points, but they are critically and contiguously arranged at one end of the nails.
The feeding can be done by gravity, if the nails are loose, or by mechanical means engaging the nail heads and shanks at the level of the contact points to provide clip-forming supports such as adhesive tape or frangible mastics, etc. Moreover, a lot of available clip storage space for nails is not utilized because of the wide spaces between the nail shanks. The spacing is at least the radial distance of the head overhanging the shank.
Where a supporting means for spaced shanks is used, waste material has to be disposed of as the lead nail is stripped free each time for driving, and, although heads have been provided having the same width as the nail shank, the holding power of the reduced head area is greatly reduced to a fraction of what may be desired of a common nail having a shank of the rated diameter involved.